Our solar system consists of one star (the Sun), nine planets and all their moons, several thousand minor planets called "Asteroids"or "Planetoids",
and an equally large number of Comets. The Sun's age was calculated in 1989 to be 4.5 billion years old, less than the 4.7 billion years previously believed. It was formed from a
cloud of hydrogen mixed with small amounts of other substances that had been produced in the bodies of other stars before the Sun was born. This was the parent cloud of the solar
system. The dense, hot gas at the center of the cloud gave rise to the Sun; the outer regions of the cloud—cooler and less dense—gave birth to the planets.

Our Sun is about 4.5 billion years old, and derives its energy from the nuclear reactions taking place between hydrogen and helium at the core. Its
core has a temperature of about 15 million degrees Celsius, with the surface, or photosphere, at about 6,000ºC. The Sun's diameter is 1,392,000 kilometers and it contains 99.86% of
the mass of our whole solar system.

The Sun has several layers: the core, the radiation zone, the convection zone, and the photosphere (which is the surface of the Sun). In
addition, there are two layers of gas above the photosphere called the chromosphere and the corona.

In the nuclear reactions that occur at the core, about 700 million tons of
hydrogen is converted to helium every second, and since helium is about 7% lighter, this means that some 5 million tons of matter/sec is converted into pure energy. This energy takes
about 10 million years to travel from the core to the Sun's photosphere, a 500km thick layer from which most of the Sun's radiation and light finally escape.

Above the photosphere lies the chromosphere, where flares, prominences and sunspots arise, the temperature steadily increases with altitude up to about 50,000
ºC.

Solar flares are spectacular discharges of magnetic energy from the corona. These discharges send streams of protons and electrons outward into space. Solar flares can
interrupt the communications network here on Earth.

Solar prominences are storms of gas which erupt from the surface in the form of columns which either shoot outward into
space or twist and loop back to the Sun's surface.

Sunspots are magnetic storms on the photosphere that appear as dark areas because of their lower temperatures of around
4,800ºC. Sunspots regularly appear and disappear in eleven-year cycles.

Solar winds are the result of gas expansion in the corona. This expansion leads to ion formation. These ions are hurled outward from the corona at over 500 kilometers per second.

Beyond the chromosphere, with temperature increasing again, lies the corona, extending outward from the Sun in the form of the Solar Wind to the edge of the solar system.

The Sun rotates every ~27 days, but because it is a large gaseous sphere, the equator rotates faster than the poles. This is known as a differential rotation. Its activity rises and
falls over an eleven year cycle (approx.) producing variations in the Earth's magnetic field and changes to the ionosphere (upper atmosphere) affecting radio communications. This changing
activity is associated with the production of sunspots.

The Sun gives off many kinds of radiation other than light and heat. It also emits radio waves, ultraviolet rays, and X-rays. The Earth's atmosphere protects us from the harmful
effects of the ultraviolet rays and the X-rays.

Mercury

Mercury is the closest planet to the sun. It is very hot. It is only 57,900,000 Km (36,000,000 miles) away from the sun. It hurtles around the sun at a speed of 170,000km/h
(105,600 mph). If it were any closer, the planet would burn up into the suns blasting heat. Its nearest distance to earth is 45,000,000 Km (28,000,000 miles).

Each day lasts 59 earth days and a year lasts 88 earth days. It is always hot. Its average temperature on the lit side of the planet is 350°C (660°F). This hot temperature can get to
be six times hotter than earth. Its average temperature on the dark side is -170°C (-275°F). Mercury has no atmosphere, to trap the heat in. The cold can be ten times colder than the inside of a
freezer. The diameter across the planet is 4,878 Km (3,031 miles).

Along with Mars, Venus and Earth, Mercury, they are known as the inner planets, as they are nearest to the sun. They form a group of rocky planets.

Mercury's density is 5,440 Kg per cubic square metre (11,990 pounds per cubic yard). This is 5.44 times as dense as water.

Venus

Venus is the planet that comes closest to the earth 42,000,000 km. it is almost the same size as the earth, yet the two planets are completely different. Venus rotates very slowly in
the opposite direction from earth, once every 243-earth day. Apart from the moon, Venus is by far the brightest object in the night sky.

The temperature of the surface is 480°C. The atmospheric pressure is nearly 100 times than that on earth and is made up of mainly carbon dioxide. The heavy atmosphere lets in
solar energy to heat up the surface but then traps the heat so that's why Venus is the hottest planet in our solar system! It is so hot that it could melt lead.

Venus is 6,052 km wide which is almost the same size of the earth.

Venus does not have any moons like mercury, and it rains concentrated sulphuric acid that would dissolve us if we landed there.

There were once oceans on Venus but these have long since boiled away due to the great heat on the surface.

In it's early days Venus was just like earth it had oceans and may even held life, but as it has so much carbon dioxide in it's atmosphere, all the oceans have gone so would any life.

Earth

Earth is the 5th largest planet in our solar system. LUNA the earth's moon is our closest neighbour. Its average distance from earth is 384,00 Km (239,000 miles). The moon takes 27 days to travel round the earth.

This is the only planet we know which has living things on it. It started off as tiny 'single-celled' organisms, now over a period of billions of years those little organisms have
grown into more and more complex creatures. Earth is filled with lots of living things such as plants and animals.

Mars

Mars is small when compared to earth. it is 249,000,000 kilometres (155,000,000 miles) away from the sun. Mars is Earth's neighbour. The furthest distance that has been
recorded from Mars to Earth is400,000,000 kilometres (249,000,000 miles).

Mars' day is calculated at 24 hours and 37.5 minutes. It tilts at an axis of 23.98 degrees. Summer and spring last for 381 days and autumn and winter last 306 days, which
makes it cold most of the time. It takes 687 Earth days for Mars to orbit the sun.

The average daytime temperature is -23 degrees F (-10 degrees C) and the average night-time temperature is -101°F (-10°C). Mars has two moons, their names are Deimos and Phobos.

It tilts on an axis of 24°F. Its atmosphere is made up of mainly Carbon Dioxide.

Jupiter

Jupiter is the fifth planet from the sun and is about 770 million kilometres from it. It takes almost twelve years for Jupiter to orbit the sun. Jupiter is larger than planet
earth, it spins in less than 10 hours, whereas Earth spins in 24 hours. This is the fastest of any planet. This rapid spinning causes powerful winds that pushes the clouds into colourful bands,
streaks and swirls that circle planet. The temperature on the surface is very cold about 150 degrees below freezing and that's in the daytime! The centre of Jupiter is very hot, It is
over 28,000 degrees. Jupiter is made up mostly from hydrogen. These are always moving. It takes approximately four months for the clouds to travel one thousand kilometres West.

The red spot has always been a great mystery to astronomers. It was first seen over one hundred years ago through a telescope from earth. No one knows how or when it was formed. It
is thought that it is an enormous storm, a massive hurricane, much more powerful than anything that we experience on earth, that is twice as big as our planet. Over the past years, it has shrunk,
grown, become brighter, become duller. It does not change position, though.

Jupiter has sixteen moons and many more waiting to be discovered. The smallest moon is under 80 kilometres across. The four largest moons - Io, Europa, Ganymede and Callista circle
close to the planet. These are called the Galilean moons, after being discovered by the great Italian scientist Galileo, who saw them in 1610 with his small, home-made telescope. Other Jupiter
moons are Metis, Adrastea, Amalthea, Thebe, Io, Europa, Ganymede, Callisto, Sinope, Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae W1302, W1700, W1704, W1704_2, W1800, W1903_s, W1805,
W1902, W1904, W2002_2, and W1700_2.

Saturn

Saturn is the second biggest planet in our solar system. It's a massive 95 times heavier than earth and the volume is 750 times the earth. Saturn is a favorite object for many
observers. It's beautiful rings are 169,800 miles wide, but less thick than a football field. In many ways Saturn is similar to Jupiter, but it is much smaller. Under the clouds of methane
and helium the sky gradually turns into liquid until it becomes a giant ocean of liquid chemicals. It takes a whole 29 years and 167 days for Saturn to orbit the sun.

The length of just one-day is 10 hours and 14 minutes. One year lasts for 29.5 earth days. It has 18 named moons and even more un-named moons. The atmosphere is made up of hydrogen
and helium, and the core temperature is a tremendous 12,000° C (22,000° F). That is very hot.

Galileo Galilei, who was at the time looking in the direction of Saturn in 1610, discovered the orange planet. Giovanni Domenico Cassini discovered gaps between Ring A and B in 1975,
which leaves a gap of 4,000-Km (2,500 miles). Ring A is an immense 15,000 Km (9,300 miles) wide. The rings are made up from ice particles. Which are shaped by the 1,600km/h (1,000-mph) winds.

Uranus is almost identical to the planet Neptune. Uranus is very odd. Unlike all the other planets and most of the moons in our Solar System Uranus spins on its side. It
is believed that long ago a very large object smashed into this planet. The crash was so powerful that it completely changed the direction of Uranus' spin. Uranus may have an ocean of water
beneath its clouds. It has a large rocky core, and because of the tremendous pressure could possibly contain trillions of large diamonds.

Uranus is a massive 2,870,000,000 km (1,783,000,000 miles) from the sun. The average temperature of the clouds is –140° C (-220° F).

It's diameter across the equator is 52,000 km (32,000 miles) and the atmosphere is made up of hydrogen (H) and helium (He). Hydrogen makes up 84% of the atmosphere, He 14%, and 2% is
of methane. The atmosphere is thought to be 10,000 km deep (6,200 miles).

It has 21 moons. Five of these moons are large, and the rest are smaller. Their names are Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind,
Belinda, Puck, Miranda, Ariel, Umbriel, Titania, Oberon, Caliban, Sycorax, Prospero, Setebos, Stephano, and 1986U10.

Neptune

It is the second from last planet in our solar system. The nearest distance that Neptune is to the earth is 4,350,000,000 km (2,700,000,000 miles). The average temperature of the
clouds on Neptune is –210° C (-350° F) Neptune has a giant storm much like the storm on Jupiter. This storm is often called The Great Dark Spot. We do not know how long
this storm has been active, because it is so far away that we could not get a good view of Neptune until modern times when we began to send robot explorers. For many centuries people did not know
that this planet even existed. It was discovered by Johann Galle and Heinrich D'Arrest in 1846.

Neptune has six rings which circle the planet. The distance from the sun to the blue planet is 4,500,000,000 km (2,800,000,000 miles).The diameter is 48.600 km (30,200 miles). Its
atmosphere is made up from H, He and Me. It has 2 moons and 6 moonlets! (which is a very small moon). One day 24 hrs, lasts for 16 hours 3 minutes and one year lasts 164 earth years.

Neptune has eight moons that we know of. Because Neptune is so far away, it is difficult to see any of these worlds. There are probably many more moons orbiting this blue
planet which we have not yet discovered. The names of the known moons are: Caliban, Sycorax, Prospero, Setebos, Stephano, and 1986U10.

Pluto

Pluto is smaller than 7 of the moons in the Solar System. Because it is so small many scientists don't consider it a planet at all. In 1999 a group of scientists
attempted to redesignate Pluto as a comet.

It was discovered in 1930. Its mass is much larger than Earth. which is surprising, considering that Earth is three times bigger. Even the moon is larger.

Pluto only has one moon - Charon. It was named after the character in Greek mythology who was a ferryman in the realm of Pluto. Charon has a diameter of 1,186 Km (736 miles), more
than half of Pluto.

Pluto is known to have a density just over twice that of water, indicating that it contains a rocky core. Its mantle is made, probably, of water and Methane. Its atmosphere probably
consists of methane in a gaseous form, together with heavy gases such as nitrogen, argon, carbon monoxide and oxygen. Its surface temperature is around -216°C (-355°F).